The present invention relates to the new chlorohydrosilane derivatives having the following formula (I) and a preparation method thereof. The chlorohydrosilane derivatives of the formula (I) of the present invention which have both of the Si--H and Si--Cl bonds in their molecular structures are prepared by reacting chlorosilane of the following formula (II) which has at least two Si--Cl bonds with lithium aluminum hydride (LiAlH.sub.4). Because a Si--H bond enables the hydrosilylation reaction with the unsaturated organic compounds and a Si--Cl bond can participate in hydrolysis or the reaction with a nucleophilic compound such as Grignard reatent, the chlorohydrosilane derivatives of the present invention which have both of the aforementioned bonds are important organo silane compounds which can be employed in manufacturing various compounds. ##STR2## wherein R.sup.1 is straight, branched or cyclic alkyl group having 1 to 30 carbon atoms which can include an aromatic group or heterocyclic group, and R.sup.2 represents chloro group, straight, branched, or cyclic alkyl group alkyl group having 1 to 30 carbon atoms, which can include an aromatic group or heterocyclic group.
Generally, a Si--Cl bond is converted into a Si--H bond by using a reducing agent such as lithiumaluminumhydride (C. Eaborn, "Organosilicon Compounds", Academic Press Inc., New York, 1960). A typical method comprises drop addition of silane compounds into a flask which contain lithiumaluminum hydride in a solvent such as ethylether or tetrahydrofuran in a room temperature or under reflux temperature. EQU 4Me.sub.3 SiCl+LiAlH.sub.4 .fwdarw.4Me.sub.3 SiH+LiAlCl.sub.4
It has been known to be difficult to partially reduce a halogen group of a silicon compound having at least two halogen groups by using lithiumaluminum hydride. McCusker and his colleagues reported that although they tried to prepare chlorohydrosilane by partially reducing an excess amount of ethyltribromosilane with a small amount of lithiumaluminum hydride at low temperature, only they obtained were totally reduced ethylsilanes [P. A. McCusker and E. L. Reilly, J. Am. Chem. Soc.,75, 1583(1953)]. ##STR3##
In addition, Opitz and his colleagues reported that they failed to get partially-reduced chlorohydrosilane even though they reacted an excess amount of tetrachlorosilane by using lithiumaluminumhydride or calciumhydride at low temperature [H. E. Opitz J. S. Peake and W. H. Nebergall, J. Am. Chem. Soc., 78, 292 (1956)].
The redistribution reaction of a silicon compound is a reaction wherein each of the hydrogen, halogen, phenyl, or alkyl group attached to silicon are mutually exchanged in the presence of a metal catalyst.
Whitmore and his colleagues reported on the synthesis of diethylchlorosilane and diethylsilane by redistribution of diethyldichlorosilane and triethylsilane in the presence of aluminum chloride catalyst. (F. C. Whitmore, E. W. Pietrusza, and L. H. Sommer, J. Am. Chem. Soc. 69, 2108(1947)). ##STR4##
In addition, Borisov and colleagues reported that exchange reaction of Si--H and Si--Cl easily occurs in the presence of aluminum chloride catalyst. (S. N. Borisov, M. G. Voronkov, and B. N. Dolgov, Doklady Akad. Nauk S.S.S.R. 114, 93(1957)). ##STR5##
In another example, Ponomarev and his colleagues reported that the reaction of phenylchlorosilane and methylchlorosilane at 250.degree.C. in the presence of lithiumaluminum hydride catalyst resulted in the redistribution into the compounds having both phenyl group and methyl group. (V. V. Ponomarev, V. N. Penskii, S. A. Golubtsov, K. A. Andrianov, and E. N. Chekrii, Izv. Akad. Nauk SSSR, Ser. Khim. 1972,1379)
While studying the partial reduction of chlorosilane compounds with the known reaction as aforementioned, the present inventors have found that a partially reduced silane compound can be obtained as a main product in case the lithiumaluminum hydride and chlorosilane compound are reacted at high temeprature without using solvent. ##STR6##
The compounds of general formula (I) are very important intermediates in organosilicon chemistry, because Si--H of the general formula (I) compounds makes it possible to easily introduce an organic group through the hydrosilylation with unsaturated organic compounds.
The inventors of the present invention previously invented a preparation method of a new (2-arylpropyl) alkylsilane derivatives by hydrosilylating (2-arylpropyl) silane derivatives and olefin compounds (I. N. Jung, B. R. Yoo, B. W. Lee, S. H. Yeon, U.S. Pat. No. 5,386,050(1995)). ##STR7##
By subjecting the (2-arylpropyl)alkylsilane derivatives to partial reduction according to the present process and then to a hydrosilylation reaction, it becomes possible to prepare new organosilicon compounds to which various alkyl groups have been introduced. Further, the inventors of the present invention invented a catalyst system for olefinic polymerization wherein organosilicon compounds are used as an electron donor. (I. N. Jung, J. S. Han, E. J. Cho, Y. T. Jeong, K. K. Kang, U.S. Pat. No. 5,556,822(1996)).
As an organosilicon compound used as an electron donor, it can be generally mentioned a dialkyldialkoxysilane compound which can be easily prepared by partially reducing alkyltrichlorosilane compound by means of this method of the present invention, and introducing alkyl group through hydrosilylation and then, conducting alcohollization reaction.
A typical reaction process of the present invention comprises reacting chlorosilane compound of the formula (II) with lithiumaluminum hydride in the amount of 30 to 50 mole % of the chlorosilane compound (II) in a flask equipped with a reflux cooling device under nitrogen atmosphere while heating to 100 to 200.degree. C. Optionally, aluminum chloride can be added in the amount of 5 mole % relative to the silane compound. If a chlorosilane compound of the formula (II) cannot be heated above 100.degree. C. due to its low boiling point, it can be reacted in a sealed autoclave made of stainless steel. The reaction state is monitored by a gaseous element analyzer, and when the products reach equibrium state, temperature is decreased, and non-polar solvent such as normal hexane is added so as to solve the products, which then is filtered to remove the solvent, and followed by a distillation under vacuum or atmospheric pressure to isolate the final products.
The invention will be understood more readily with reference to the following examples; however these examples are intended to illustrate the invention and are not to be construed to limit the scope of the invention.